Acetate inhibition is a well-recognized impediment to the efficient fermentation of most types of biomass, particularly those with high hemicellulose contents. The release of acetic acid during the acid, heat and pressure-induced breakdown of hemicellulose is known to produce levels of acetic acid which can exceed 1%, a level which is highly inhibitory (in terms of growth, viability and/or performance of desired metabolic function e.g. fermentation of sugars) to most microorganisms. Solutions to the problem include efforts to block the initial release by altering the pretreatment conditions, removal of acetate by chemical or physical methods and genetic improvement of the fermentation organisms to utilize or better tolerate acetate.